CN105301896A - Metallic glass film phase-change material-based photoetching method - Google Patents

Abstract

The invention discloses a metallic glass film phase-change material-based photoetching method, and belongs to the field of a semiconductor micro-nanofabrication; in the prior art, an etching edge of a multilayer film is fuzzy and is not steep enough; the method uses Pr-based metallic glass phase-change material film is used as a photoresist, Pr-based metallic glass is a metallic glass phase-change material with high stability and a low crystallization temperature, and is suitable for laser direct writing exposure heating-induced phase transition; the thermal conductivity is high, and a linewidth of a crystallization pattern can be accurately controlled by changing the laser power; the method has the characteristics of nontoxicity and innocuousness, and does not pollute the environment; the etching selectivity ratio is high and reaches 5:1, the process is simple and controllable, the production period is short, and the method is very suitable for the phase transition photoetching technology.

Description

A kind of photoetching method based on metallic glass thin film phase change material

Technical field

The invention belongs to semiconductor micro-nano manufacture field, more specifically, relate to a kind of based on etching selection ratio high in specific etching liquid, the photoetching method of phase-change material photoresist Pr-base metal glass film simple to operate.

Background technology

In the manufacture process of the micro-nano equipment such as current semiconductor devices, optoelectronic device, mems device, photoetching process is wherein one of most important technology.In order to prepare micro-nano aperture, the method for current main flow is divided into three kinds: beamwriter lithography, focused ion beam lithography, optical lithography.

Because beamwriter lithography and focused ion beam lithography need to carry out under strict vacuum environment, if vacuum tightness cannot reach standard, the accumulation of dust on optical device can cause the distortion of institute's needle drawing case; Apparatus expensive, and photoetching efficiency is very low, is not suitable for business-like production in enormous quantities.Therefore the still optical lithography be most widely used so far.

Traditional optical lithography is using the ultraviolet light of 200nm ~ 450nm as photolithography light source, utilize photoresist (being commonly called as photoresist) to realize the conversion of figure, transfer and process as intermediary, finally image information is delivered to a kind of technique on wafer (mainly referring to silicon chip) or dielectric layer.It can reach minimum resolution and be determined by following formula:

$R=\frac{k_1\mathrm{\λ}}{NA}$

Wherein R is optical resolution, and λ is lithography laser wavelength, and NA is the numerical aperture of focusing objective len.According to formula, directly effectively resolution can be reduced by the method reducing laser wavelength lambda and raising numerical aperture NA.But when optical maser wavelength is reduced to ultraviolet and deep ultraviolet wave band, conventional optical component absorbs very strong at this wave band, must adopt CaF ₂etc. saturating uv materials, considerably increase photoetching cost; And the aerial ultimate value of numerical aperture is 1.0, used 0.9 does not have too large room for promotion yet at present.Therefore, in order to the development of satisfied science and technology and the continuity of guarantee Moore's Law, Emerging Photoetching Technology is being put into large quantifier elimination.

Phase transformation photoetching utilizes inorganic phase-changing material (as GeSbTe) to be deposited on substrate surface as photoresist with appropriate thickness, then the laser beam that can modulate is utilized to expose phase change material film according to required character pattern, after laser explosure, exposure area can undergo phase transition because laser pyrogenicity makes temperature exceed phase transition temperature, and unexposed region is still for amorphous state remains unchanged, film is immersed among etching liquid, utilize exposure area (crystalline state) and the etching difference of unexposed area (amorphous state) among etching liquid to complete the preparation of micro-nano structure.

The research majority of current phase transformation photoetching is all based on sulphur based semiconductor phase-change material (as GeSbTe, AgInSbTe etc.) and multi-layer film structure thereof, the etching selection ratio (i.e. the etch rate ratio of two-phase) of sulphur based semiconductor monofilm material is not high, approximately only have about 2, and the etched edge of multilayer film is fuzzy, precipitous not.Therefore, the research of New-type phase change photoetching material seems particularly important for the development of phase transformation photoetching.

Summary of the invention

Etched edge for the multilayer film of prior art is fuzzy, precipitous not, and object of the present invention is being intended to the problem solving above technology.

For achieving the above object, the invention provides a kind of photoetching method based on metallic glass thin film phase change material, it is characterized in that, said method comprising the steps of:

(1) metallic glass noncrystal membrane described in one deck is deposited by magnetron sputtering in quartz substrate surface;

(2) selective laser exposure is carried out to the As-deposited film of gained, adjust described laser power and make exposure area reach crystallization temperature to undergo phase transition, produce required crystallized nano pattern;

(3) film sample of the crystallized nano pattern carrying out selectivity exposure-processed is put into prepare salpeter solution and etch, the nano-pattern needed for formation;

Wherein said metallic glass thin film phase change material is Pr-, Ni-, Nd-, La-, Pt-or Ce-base metal glass thin film phase change material.

Preferably, described salpeter solution is aqueous solution of nitric acid or nital;

Preferably, prepare the red fuming nitric acid (RFNA) that nitric acid used in described aqueous solution of nitric acid is 65%, wherein, the volume ratio of red fuming nitric acid (RFNA) and water is 1:180, and the massfraction of the aqueous solution of nitric acid prepared is 0.5%.

Preferably, described etching temperature is room temperature to 40 DEG C, and the time is 5s-50s.

By the above technical scheme that the present invention conceives, compared with prior art, following beneficial effect can be obtained:

Utilize Pr-base metal glass phase change material film as photoresist, Pr-base metal glass is the metallic glass phase-change material that a kind of thermal stability is high, and crystallization temperature is lower, is applicable to the phase transformation of laser direct-writing exposure pyrogenicity; Thermal conductivity is higher, is conducive to by changing the accurate controlling crystallizing pattern line-width of laser power; Nontoxic, environmentally safe; Etching selection ratio is high, can reach the etching selection ratio of 5:1, is highly suitable for phase transformation photoetching technique.

Accompanying drawing explanation

Fig. 1 is that Pr-base metal glass phase-change material uses process flow diagram as photoresist;

Fig. 2 is the metaloscope figure that PrAlNiCu phase-change material noncrystalline membrane carries out the rear crystallization of laser direct-writing exposure;

Fig. 3 is the XRD collection of illustrative plates comparison diagram before and after the exposure of PrAlNiCu phase change material film;

Fig. 4 is the curve comparison figure of PrAlNiCu noncrystalline membrane and crystalline film etch amount and etching time in the salpeter solution of 0.5% massfraction.

Embodiment

In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.

As shown in Figure 1, one deck Pr-base metal glass noncrystal membrane is deposited in quartz substrate surface by magnetron sputtering, selective laser exposure is carried out to the As-deposited film of gained, adjustment laser power makes exposure area reach crystallization temperature to undergo phase transition, produce required crystallized nano pattern, the part namely exposed becomes crystalline state from amorphous state; The film sample of the crystallized nano pattern carrying out selectivity exposure-processed is put into the salpeter solution preparing special ratios etch, put into clear water cleaning after having etched and dry up, finally prepare required nano-pattern.

Further, described salpeter solution is aqueous solution of nitric acid or nital, preferred aqueous solution of nitric acid;

Further, nitric acid used in the aqueous solution of nitric acid of described preparation is the red fuming nitric acid (RFNA) of 65%, and wherein, the volume ratio of red fuming nitric acid (RFNA) and water is 1:180.The massfraction of the aqueous solution of nitric acid prepared is 0.5%.

Further, described etching temperature is room temperature to 40 DEG C, preferably 25 DEG C.

Further, in salpeter solution, etching time is 5s-50s.

Further, described exposure uses laser writing technology;

(1) optical maser wavelength used is 661nm;

(2) Laser Focusing camera lens numerical aperture used is 0.4;

(3) described laser power is 30mW-80mW;

(4) described Laser exposure dwell times is 50us-2ms.

Further, this photoetching method, except being applicable to Pr-base metal glass, is also applicable to Ni-, Nd-, La-, Pt-or Ce-base metal glass.

Further, Pr-base metal glass film adopts Pr-base metal glass target, utilizes magnetron sputtering to prepare in monocrystal silicon substrate deposition.

Further, described film thickness is 200nm-400nm, preferred 300nm.

Embodiment 1:

Utilize the method for magnetron sputtering in the quartz substrate of thickness for 1mm, sputter the PrAlNiCu metallic glass film of one deck 300nm.Wherein, concrete sputtering parameter is d.c. sputtering (DC), Ar Pressure 0.3pa used, sputtering power 60W, and target-substrate distance is 120mm, and sputtering time is 15 minutes, pre-sputtering 15 minutes before sputtering.

Laser is utilized to expose, concrete steps are: by LASER Light Source being fixed, sample is placed on removable motor, the required nano-pattern step sequence obtained is imported computing machine, computing machine is utilized to carry out step motion control to motor, thus to required nano-pattern carry out selectivity exposure directly write, utilize metallography microscope sem observation figure after Figure 2 shows that exposure.As shown in Figure 3, XRD collection of illustrative plates (a) before exposure is level and smooth without protruding, is amorphous state; XRD collection of illustrative plates (b) after exposure demonstrates obvious diffraction peak, is crystalline state.

Be placed in the aqueous solution of nitric acid prepared by sample after exposure and etch, the massfraction of salpeter solution is 0.5%, and etching time is respectively 5s, 10s, 15s, 20s, 25s, 30s, 35s, 40s, 45s, 50s.The etch amount of each time point as shown in Figure 4.

As shown in Figure 4, along with the increase of etching time, the amount of etching is also increasing linearly, but the etch rate of amorphous etch rate and crystalline state is also inconsistent, the etch rate of amorphous state PrAlNiCu is about 10.053nm per second, and the etch rate of crystalline state PrAlNiCu is about 2.004nm per second, the etching selection ratio of PrAlNiCu in etching liquid of amorphous state and crystalline state is about 5:1, presents splendid phase transformation photoetching potentiality.

Those skilled in the art will readily understand; the foregoing is only preferred embodiment of the present invention; not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.

Claims (7)

1. based on a photoetching method for metallic glass thin film phase change material, it is characterized in that, said method comprising the steps of:

(1) layer of metal glass noncrystal membrane is deposited by magnetron sputtering in quartz substrate surface;

(2) selective laser exposure is carried out to the As-deposited film of gained, adjust described laser power and make exposure area reach crystallization temperature to undergo phase transition, produce required crystallized nano pattern;

(3) film sample of the crystallized nano pattern carrying out selectivity exposure-processed is put into prepare salpeter solution and etch, the nano-pattern needed for formation.

2. the method for claim 1, is characterized in that, described metallic glass thin film phase change material is Pr-, Ni-, Nd-, La-, Pt-or Ce-base metal glass thin film phase change material.

3. the method for claim 1, is characterized in that, described salpeter solution is aqueous solution of nitric acid or nital.

4. the method for claim 1, is characterized in that, prepares the red fuming nitric acid (RFNA) that nitric acid used in described aqueous solution of nitric acid is 65%, and wherein, the volume ratio of red fuming nitric acid (RFNA) and water is 1:180, and the massfraction of the aqueous solution of nitric acid prepared is 0.5%.

5. the method for claim 1, is characterized in that, described etching temperature is room temperature to 40 DEG C, and the time is 5s-50s.

6. method as claimed in claim 2, is characterized in that, described Pr-base metal glass thin film phase change material adopts Pr-base metal glass target, utilizes magnetron sputtering to prepare in quartz substrate deposition.

7. method as claimed in claim 2, it is characterized in that, the thickness of described film is 200nm-400nm.